The present invention relates in general to synchronizing devices and more particularly to an improved thrust member of establishing preliminary frictional engagement in such a device prior to positive locking engagement between a pair of tooth clutches.
Synchronizing devices of this type are well known and normally have a friction portion consisting of a pair of cone-type friction rings releasably connected to a positive coupling portion in the form of an axially shiftable clutch collar. The friction portion facilitates clash-free shifting between clutch teeth on the coupling collar and mating clutch teeth on an associated gear by initially engaging appropriate friction means on the gear to either speed up or slow down the mating elements until the speeds are approximately equal. When this occurs the friction portion is released and the clutch teeth engage. In such arrangements the fricton rings are rigidly held in axially spaced relation by a plurality of circumferentially disposed solid pins. The coupling collar, which is the positive clutch portion of the synchronizing device, is located between the friction rings and has openings through which the pins extend. Coacting blocking shoulders are normally provided on the pins and within the openings. In shifting, the initial axial motion is transmitted from the coupling collar to the friction rings by a plurality of thrust members. These thrust members carry the friction rings toward the gear to be engaged until sufficient contact is made with the mating friction surface on the selected gear. The accelerating force of the friction ring driving the selected gear results in a limited rotation of the friction rings relative to the coupling collar causing the blocking shoulders in the openings to lock with those on the pins. Continued pressure on the gear shift lever forces the friction surfaces firmly together by means of the blocking shoulders so that the friction ring and selected gear approach the same speed. When substantial synchronization occurs, the load on the blocking shoulders is relieved allowing the clutch collar to pass over the blocking shoulders on the pins to complete the shift.
Thrust members for synchronizing devices of the above type have taken many forms including flat stamped spring loaded members, the more common spring loaded plunger type and those utilizing a split-pin design consisting of a pair of semi-cylindrical halves which are biased apart within the openings by separate resilient means.
These prior designs are generally satisfactory functionally but are costly and present assembly and possible replacement problems due to the multiplicity of parts involved.